Roof Ventilation Tips

Depending on the type of roof on your home or building, there are a wide range of roof ventilation systems utilized in construction today.  The information about roof ventilation can be overwhelming for non-experts, and it can be very easy to become frustrated or confused about the whole thing.  When and where you should use ventilation, what kind of ventilation is best for your roof, and even the reasoning behind ventilation may escape you.  So let’s take a little time to discuss roof ventilation and how it applies to different types of construction.

Why is Roof Ventilation Important?

The theory behind roof ventilation is essentially temperature control.  In a cold climate, roof ventilation helps to prevent ice dams by maintaining a cool roof temperature and also allows moisture to escape from conditioned living spaces through the attic.  On the other hand, in hot climates, proper ventilation allows for solar-heated hot air from the attic to escape thereby reducing a building’s cooling load and limiting strain on air-conditioning systems.  Roof ventilation can even serve both roles in regions where climates range from hot to cold.

Types of Roof Ventilation

Depending on the building codes of your region, you’ll likely need one square foot of vent area for every 150 square feet of attic space.  Ventilation exists not only for air to escape, but also for air to enter.  There are several types of roof ventilation, which we will discuss now.

  • Box vents are also known as low profile vents, louvers, flat vents, or even turtle vents.  They are known as static vents because they have no moving parts.  A box vent covers a hole cut out of the roof and they utilize natural convection for air movement.  Available in a variety of colours and constructed from a range of materials, box vents are versatile, inexpensive, and one of the most common types of roof ventilation system.
  • Wind turbines are sometimes known as whirlybirds, and while they include moving parts, they do not feature a motor and instead rely on wind to power movement.  These types of ventilation systems move more air than traditional box vents providing the wind is blowing.
  • Power vents combine some of the benefits of box vents and wind turbines.  Because they are motor driven, they ensure proper ventilation regardless of the climate or wind conditions.  While they are quite and efficient, but somewhat more expensive than box vents or whirlybirds.
  • Ridge vents are another type of static vent system that is installed along roof ridges.  They are designed to run the full length of a roof’s horizontal ridge and blend seamlessly into a roof’s design making them an attractive option.
  • Off-ridge vents are similar to box vents in that they are static vents installed over a cut section of the roof, usually near the ridge.  Still, box vents are square whereas off-ridge vents are thin and rectangular, and perhaps the least efficient of roof vents.

As you can see, roof ventilation systems are varied and complicated, so it is always best to work with a qualified roofing contractor when considering which system is best for your home.  Your contractor can tell you which systems are best in your climate and even for your type of roof.